Date: Sun, 30 Dec 2007 15:30:52 +0100 From: Kris Kennaway <kris@FreeBSD.org> To: Gergely CZUCZY <phoemix@harmless.hu> Cc: Jeff Roberson <jroberson@chesapeake.net>, freebsd-performance@freebsd.org Subject: Re: mysql scaling questions Message-ID: <4777AB9C.1010003@FreeBSD.org> In-Reply-To: <20071230141118.GA67574@harmless.hu> References: <20071201205609.GA54238@harmless.hu> <200712012108.lB1L8qAd005766@lava.sentex.ca> <20071201211012.GA55519@harmless.hu> <20071201122122.S884@192.168.1.107> <20071204130810.GA77186@harmless.hu> <47779AA7.2060801@FreeBSD.org> <20071230132451.GA61295@harmless.hu> <47779EBC.5020900@FreeBSD.org> <20071230134354.GA63555@harmless.hu> <4777A65C.8020406@FreeBSD.org> <20071230141118.GA67574@harmless.hu>
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Gergely CZUCZY wrote: >>>> Still waiting for your sysbench command lines :) >>> There were 2 scripts and a sources file with options: >>> basicall that's everything. I know it's a but complex, but this was all behind it. >> OK, that was very important since you're changing defaults. > For different configurations, yes. But every test is heterogenous. I meant important from the point of view of others being able to repeat your tests. >> It looks like myisam is doing huge numbers of concurrent reads of the same file which is running into exclusive locking in the kernel >> (vnode interlock and lockbuilder mtxpool). Does it not do any caching of the data in userspace but relies on querying into the kernel >> every time? innodb doesn't have this behaviour. > Sorry, but was this a rethorical kind of question, or was this addressed to me? :) > If the later, then how do I find this out? It's a general question. It looks like myisam either has a design deficiency in this regard or it has poor defaults. If it can be made to improve caching of the data in userland then performance should improve. Kris
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